Preferred fits H/JS/G/F/D up to Ø 3150 mm, with clearance and interference per band.
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Questions
What is the hole-basis system in ISO 286?+
The hole gets an H tolerance zone (lower deviation EI = 0). The shaft (c, d, f, g, h, k, n, p, s) decides whether the fit is clearance, transition or interference.
What does H7/g6 mean?+
Clearance fit: hole H7, shaft g6. Always clearance. Typical for sliding or accurately movable parts.
Why are 30–40 mm and 40–50 mm separate?+
IT grades are the same for 30–50 mm (H7 = 25 µm). The fundamental deviation of c changes at 40 mm, so H11/c11 has two rows.
Is H7/p6 always interference?+
Not always. In the supported table bands above 3 through 18 mm, maximum clearance is 0 µm: line fit is possible. Above 18 through 50 mm there is always interference. The above 0 through 3 mm band is disputed; p6 values above 50 mm are unavailable.
Are the values in mm or µm?+
Tables and calculator are in mm, converted from ISO 286 (µm). JS7 shows four decimals where IT7 is odd.
Calculator
Nominal fit
Nominal Ø in mm, above 0 up to 3150 mm. In the smallest band (>0–≤3 mm) only H6–H11, JS7, h6 and h7 are included as table values. p6 is derived and disputed there; other classes show "—".
Ø 20 mm · band >18 – ≤30 mm · Clearance — always clearance
Hole H7
+0,021 / +0,000 mm
Shaft h6
+0,000 / -0,013 mm
Clearance min … max
+0,000 … +0,034 mm
Ø20H7
20,000 / 20,021 mm
Ø20h6
19,987 / 20,000 mm
Location fit. Sliding with minimal clearance; locating stationary parts.
* only up to 50 mm (no formula for c, k, n, p or s).
Which fit, when
H11/c11· Clearance — always clearance
Generous clearance. Sheet metal work, rough assembly, painted or dirty surfaces.
H9/d9· Clearance — always clearance
Generous running fit. Pulleys, rings, parts that must run easily.
H8/f7· Clearance — always clearance
Running fit. Sliding shafts and bearings that must rotate with clearance.
H7/g6· Clearance — always clearance
Precise sliding. Little clearance, still movable by hand.
H7/h6· Clearance — always clearance
Location fit. Sliding with minimal clearance; locating stationary parts.
H7/k6· Transition — clearance or clamping
Transition. Tapped in with a hammer; centering where clearance or light clamping is acceptable.
H7/n6· Transition — clearance or clamping
Firm transition. Usually clamping; pressed or tapped in.
H7/p6· Interference — always interference
Above 3 through 18 mm: interference or line fit (max. clearance 0 µm). Above 18 through 50 mm: interference. Above 0 through 3 mm: disputed; above 50 mm: unavailable.
H7/s6· Interference — always interference
Press fit. Pressed or shrink-fitted; not intended to be taken apart.
2. Hole tolerances
Upper deviation ES / lower deviation EI, in mm. JS7 = ±IT7/2, not rounded.
H6–H11, F8, G7 and JS7 are computed from the ISO 286-1 formulas above 50 mm. * K7 and N7 have no formula and stay limited to 50 mm. In the >0–≤3 mm band, F8, G7, K7 and N7 show "—": not guessed, not yet checked against a primary source.
Diameters: above the lower bound up to and including the upper bound. JS7 is ±IT7/2 per ISO 286-2, not rounded to whole µm. d9, f7, g6, h6 and h7 are computed from the ISO 286-1 formulas above 50 mm. * c11, k6, n6, p6 and s6 have no formula and stay limited to 50 mm. Reference only, not a substitute for the standard.
† Disputed value in this band (>0–≤3 mm): p6 here is derived (not transcribed from a table). Another indexed source reportedly lists es=+12/ei=+6 µm instead of the +16/+10 used here — if that's correct, H7/p6 in this band becomes a transition fit, not a line fit. Verify against a primary ISO 286-2 table before use.
